1. 1Department of Neurological Surgery, Oregon Health & Science University, Portland, Oregon;
2. 2Neurosurgical Service, Wright Patterson Air Force Base, Ohio;
3. 3Division of Neurosurgery, Connecticut Children's Medical Center, Hartford, Connecticut;
4. 4Department of Neurosurgery, Brooke Army Medical Center, Fort Sam Houston, Texas;
5. 5Department of Neurosurgery, Madigan Army Medical Center, Fort Lewis, Washington; and
6. 6Department of Neurosurgery, Walter Reed Army Medical Center, Washington, DC